The invention generally relates to application programming interfaces (APIs) and, even more particularly, relates to a Radio Interface Layer comprising a set of APIs.
Cellular telephones are becoming commonplace in today""s world. As users become more accustomed to using cellular telephones, they are requesting more sophisticated uses of telephones. Ideally, users would like their cellular telephones to perform the same functions as their personal computers or hand-held PDAs. Implementing such uses in a cellular telephone environment requires application developers to develop or adapt their software for use on a cellular telephone. However, adapting or developing software for use on one OEM""s cellular telephone does not necessarily guarantee that the software application will function on another OEM""s cellular telephone due to the different radio implementations of different OEMs and due to the differences in different cellular environments.
In order to create a software solution adaptable to multiple different cellular systems and radios, there is a need for some kind of a hardware adaptation layer, i.e. a layer that isolates the specifics of a particular cellular system/hardware from the bulk of the software system. There is a further need to expose a predefined interface used by the software components. There is still a further need that the layer should allow hardware manufacturers to replace/modify the implementation of the hardware interface to conform to their specific hardware.
Such a layer (TAPI) already exists for use in development of general telephony systems. However, TAPI has two disadvantages making it difficult to use in a cellular environment: a significant amount of cellular-specific functionality isn""t exposed by the TAPI interface and TAPI Service Providers (TSPs) are quite difficult to implement, thus making it harder to adapt the software system to different types of hardware. Hence, there is a need for a new hardware adaptation layer which is more specifically suited to the cellular environment and which simplifies the task of adapting it to different types of hardware.
The present invention meets the above-described needs by providing a Radio Interface Layer (RIL), which is an API set providing a level of abstraction between the radio on a cell phone and the software of the cell phone. The API set of RIL is roughly based on the GSM AT interface as defined in GSM specifications 07.05 and 07.07. The API set provides access to functionality contained within a cellular telephone, such as a GSM or CDMA compatible telephone. The present invention allows applications running on an operating system in the cellular telephone to issue commands without knowledge of the underlying radio structure of the cellular telephone and without specific knowledge of the GSM-type commands. For example, the present invention allows the applications to access phonebook entries, restrict access to data and functionality using passwords, access file and message storage, and perform many other functions. The RIL is divided into a hardware-independent proxy layer, called by various software components, and a driver layer that is hardware-specific. It should be understood that an OEM may replace the driver layer with their own layer containing implementation specific to their hardware.
That the invention improves over the drawbacks of the prior art and accomplishes the advantages described above will become apparent from the following detailed description of the exemplary embodiments and the appended drawings and claims.